The present invention relates generally to flow control valves, and more particularly to a flow control valve and related methods for use in fuel injectors for internal combustion engines.
In one class of fuel injector control systems, a conduit requires different flow restriction depending on the direction of flow through the conduit. In the past, flow control valves have been formed using a first passageway and a second passageway that were connected in parallel. The first passageway included a first check valve and a first flow restrictor. The second passageway included a second check valve and a second flow restrictor. The first check valve would allow the fluid flow to flow in a first direction through the first passageway. At the same time, the second check valve would prevent flow from passing through the second passageway. Thus, the first flow restrictor would provide a first level of flow restriction. When the flow direction reversed, the first check valve would prevent flow through the first passageway and the second flow restrictor would allow flow through the second passageway. The second flow restrictor would provide a second level of flow restriction. Thus, the first flow restrictor and the second flow restrictor would provide two different levels of flow restriction.
Unfortunately, the first and second parallel passageways and the check valves and flow restrictors required a large space. They could not be easily located in the small space within a hydraulic control system. Additionally, the first and second flow restrictors would clog with solid material being carried in the fluid flow.
The present invention is directed toward overcoming one or more of the problems as set forth above.
In accordance with one aspect on this invention, a valve comprises a housing having at least first and second walls that define a cavity therein. The cavity is configured such that a cross-sectional area of the cavity taken perpendicular to a longitudinal axis of the cavity decreases from the second wall to the first wall. A port is provided in the first wall for allowing material to enter or exit a cavity, and a port is provided in the second wall for allowing material to enter or exit the cavity. A flow restrictor disposed in the cavity.
In accordance with another aspect of this invention, the valve described above comprises a flow control valve for a fuel injector.
In still another aspect of this invention, a method for controlling flow of fluid in a hydraulic device is disclosed. The method comprises providing a valve having a housing which defines a cavity therein, with the cavity having a first portion having a relatively large cross-sectional area taken perpendicular to a longitudinal axis of the cavity and a second portion having a relatively small cross-sectional area taken perpendicular to the longitudinal axis. The method further comprises flowing material through the cavity in a first direction which causes a flow restrictor disposed in the cavity to occupy a position substantially in the first portion of the cavity, whereby flow of the material in the first direction is relatively unrestricted. The method further comprises flowing material through the cavity in a second direction opposite the first direction which causes the flow restrictor to occupy a position substantially in the second portion of the cavity, whereby flow of the material in the second direction is relatively restricted.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention.